HEAT LOSS HUB · TOOLBOX
Mass Flow Rate Calculator
Heat output, flow rate and ΔT explained with the Mass Flow Rate Triangle.
Water flow rate, heat output and temperature difference are closely connected in a wet heating system.
The Heat Loss Hub Mass Flow Rate Triangle provides a simple way to explore how changing one value affects the others and can help explain the flow rates required by heat pumps and low-temperature heating systems.
What is mass flow rate?
Mass flow rate describes the quantity of water moving around a heating system over a period of time.
The amount of heat that water can carry depends on the flow rate and the difference between the flow and return temperatures. This relationship is particularly important in heat pump systems because they commonly operate with relatively small temperature differences and therefore require sufficient water flow.
What is ΔT?
In this context, ΔT is the difference between the heating system flow temperature and return temperature.
For example, a system operating with a 40°C flow temperature and a 35°C return temperature has a ΔT of 5°C.
Important
This tool is intended for educational and preliminary calculation purposes. Actual system flow requirements must also take account of heat pump manufacturer requirements, system resistance, pump performance, pipework and system design.
Do not use the calculator as a substitute for competent heating system design.
Need an accurate heat loss calculation?
Understanding flow rates is only part of heating system design. Heat Loss Hub provides independent heat loss calculations and heating system design support.